Poker is a card game in which players wager money, either real or imaginary, against each other by placing chips (representing the amount of money they wish to risk) into a central pot. The winner of the hand receives all the money in the pot, although in some games there are rules for sharing this money among the losers. Each player has the option to call, raise, or fold. In addition, a player may bluff by betting that they have a strong hand when in fact they do not.
There are countless poker variants, which differ in the number of cards dealt, whether the cards are dealt face up or face down, and how they are placed on the table. But all poker games have at least one round of betting. At the beginning of each betting interval one or more players, as designated by the rules of the particular game, must put chips into the pot.
A poker hand consists of five cards. The value of a poker hand is in inverse proportion to its mathematical frequency; the rarer the hand, the higher it ranks. In some poker games, wild cards can change the ranking of certain hands.
When more than one hand has four of a kind, the hand with the highest rank wins. If the four of a kind are of equal rank, the high card breaks the tie (i.e., four of clubs beats four of kings). This rule also applies to other types of poker hands such as three of a kind and two pairs.